How long does the router keep the rule for forwarding external packets to the internal device?

Question

Computer networks

I will describe how it works in my understanding.
When a device behind NAT sends a packet to a device with a white ip, the router (or router) stores a rule in your tablet according to which packets that arrive at its ip and a specific port are forwarded to the internal device.
Thus, a device behind NAT sends a packet to a device with a white ip. The second device responds to the first one and the packet is successfully received.
But how long does this entry persist in the table in the absence of incoming packets?

Answer 1

either by timeout or by the end of the connection